Heretofore, as a secondary battery, optimization of a positive active material, a negative active material and an organic solvent electrolyte, etc., to be used has been carried out mainly in a non-aqueous electrolyte secondary battery (lithium ion secondary battery) using an organic solvent. A produced amount of the non-aqueous electrolyte secondary battery is markedly increasing accompanying with remarkable development of digital home appliances using the battery.
However, in the non-aqueous electrolyte secondary battery, there is pointed out in danger of catching fire since it uses inflammable organic solvent electrolyte, and the organic solvent electrolyte to be used decomposes by a reaction in the electrode to expand an outer can of the battery, and occasionally it causes leakage of the electrolyte.
Thus, an all solid state secondary battery which uses a solid electrolyte has attracted attention in place of the organic solvent electrolyte. The all solid state secondary battery does not structurally require a separator, and there is no fear of leakage of the electrolyte so that no outer can is required.
The all solid state secondary battery does not use any organic solvent electrolyte for its characteristics, a battery having no danger of catching fire can be constituted, and the solid electrolyte has ion selectivity, so that there is less side reaction and efficiency of the battery can be heightened, and as a result, a battery excellent in charge-discharge cycle characteristics can be expected.
For example, in Patent Literature 1, there is disclosed a wholly solid type substrate-mounted type secondary battery having a thin-film shaped electrode and a solid electrolyte without using any lithium metal piece. In this secondary battery, a small-sized and light-weighted lithium secondary battery is intended to be prepared by forming an electrode and an electrolyte with a sputtering method, electron beam deposition method, heat deposition method, etc., whereby the constituted product is made as thin as possible.
In Patent Literature 2, there is disclosed a laminated type thin-film solid lithium ion secondary battery in which a thin-film solid secondary battery cell comprising a positive active material, a solid electrolyte and a negative active material formed by a sputtering method is laminated two or more layers. This laminated type thin-film solid lithium ion secondary battery is laminating elements so as to connect them by a series or a parallel, so that it has been said to have effects that it can be applied to a high power appliance such as electric vehicles as a high-voltage or a high-current electric source, etc. However, thin-film wholly solid lithium ion secondary batteries disclosed in these prior art references are each produced by a sputtering method, etc., so that a film-formation rate of a thin-film of an electrode or a solid electrolyte is extremely slow. For example, for producing a battery constituted by a positive active material, a solid electrolyte and a negative active material with a thickness of 1.0 μm on a substrate, the film-formation time is 10 hours or longer. It is extremely difficult to employ such a method with a slow film-formation rate for Industrial purpose in the point of productivity, as well as in the point of manufacturing costs.
On the other hand, as an all solid state secondary battery prepared by other than the sputtering method, there have been proposed a material using a sintered body as mentioned in Patent Literature 3 and Patent Literature 4. However, the technique of Patent Literature 3 is characterized in that a positive active material layer, a solid electrolyte layer and a negative active material layer are laminated so that they are in symmetric interposing both surfaces of a flat-plate flat plate shaped collector, but such a manner of lamination is not extremely practical in industrial points of view and it is clear that it is not suitable for making a multi-layered structure. Also, the technique of Patent Literature 4 is to sinter a positive electrode material containing a binder, a solid electrolyte and a negative electrode material by micro wave heating, and then, to form a positive-electrode collector and a negative-electrode collector at the outside of the sintered material, which is a single layer battery structure, and cannot be made a multi-layered structure.    Patent Literature 1: JP 10-284130A    Patent Literature 2: JP 2002-42863A    Patent Literature 3: JP 2001-126756A    Patent Literature 4: JP 2001-210360A